Photoabsorption spectra of gaseous methyl bromide, ethylene dibromide, nitrosyl bromide, thionyl chloride, and sulfuryl chloride

Abstract

reaction enthalpy of AHr0 = -13.3, -10.1, and -2.3 kcal mol-', respectively, is calculated for the dissociation into the fragments R and C1-. Dissociation reactions yielding the fragments F-, C12-, Fz-, and/or CIF-are all endothermic. On the other hand, in aliphatic chlorocarbons a very small abundance of Clz-was detected in a low-energy (0-10 eV) electron impact study with a time-of-flight mass s p e~t r o m e t e r .~~ It is interesting to note that changes of the relative attachment rates as a function of electron energy can be related to the thermodynamics of the capture reaction. For the most exothermic reaction, i.e., capture by CC&F, only a decrease in the relative ECR line intensity is observed on increasing the electron energy. The less exothermic reaction between free electrons and CClZFz, for which an activation energy of 4.5 kcal mol-l was obtained from kinetic measurements, shows a flat maximum around 0.05 eV. Only an increase in relative line intensity with electron energy is observed for the inefficient scavenger CCIFB ( Figure 1). The calculated AHro yielded -2.3 kcal mol-'. The determined activation energy was 5.7 kcal mol-'. Unfortunately, the change in relative cross section could not be followed to higher electron energies to obtain the position of the maximum.Acknowledgment. The technical assistance of Mr. C. Lygris is gratefully acknowledged.

Competitive channels in the photodissociation of thionyl chloride

“…1, extends well into the spectral range easily accessible with ultraviolet laser radiation. 26 The distinct shoulder at 40 000 cm À1 (250 nm) and the pronounced absorption maximum above 50 000 cm À1 (below 200 nm) were assigned to overlapping electronic transitions: the s* SCl n S and the p* SO n S transitions from a non-bonding lone pair electron on the sulfur atom to the anti-bonding molecular orbitals of the S-Cl or the S-O bond, and, at higher excitation energies, the corresponding transitions from a non-bonding n Cl electron out of the Cl(3p) manifold. 24,27 Photodissociation studies have been performed at wavelengths of 193 nm, 235 nm, and 248 nm, [20][21][22][23][24]28 corresponding to excitation in the short wavelength absorption maximum and the long wavelength shoulder, respectively.…”

Kinetics and Thermodynamic Studies of the Chlorination Of Sultams Using Conductivity Measurements

“…The rate constant values (k) at different temperature were calculated for the product from the pseudo first order equation [14,15] :…”

Kinetics and thermodynamic studies of the bromination of sultams using a spectroscopic technique

“…The results obtained from the kinetic data for the product of the bromination of sultams were found to follow pseudo first-order kinetics according to the equation (1). The rate constant values (k) at different temperature were calculated for the product from the pseudo first order equation [11,12] :…”